EFFECTS OF SOIL PROPERTIES AND MOISTURE ON THE SORPTION OF TRICHLOROETHYLENE VAPOR

Correlation of tricholoroethylene (TCE) vapor partition coefficients (at P/P0 < 2%) onto seven sorbents with selected properties showed that: (1) under oven-dried conditions, specific surface area best described sorption of TCE and (2) under air-dried conditions (68% r.h.), at field capacity and for saturated conditions, organic carbon content controlled sorption. The change in the dependency of TCE vapor partition coefficients, from specific surface area at oven-dried conditions to organic carbon content at air-dried conditions, is hypothesized to result from: (1) reduced sorption of TCE onto mineral surfaces because of competition with water and (2) increased importance of partitioning into organic matter. At field capacity, the sorption of TCE vapor can be accounted for by two contributions: (1) dissolution of TCE in the water bound to the sorbent as governed by Henry's law and (2) sorption of TCE at the solid-liquid interface as governed by a saturated partition coefficient. Dissolution of TCE into surface-bound water can constitute a large fraction of the total TCE uptake from the vapor phase for sorbents with low organic carbon content.